Labour's credibility on defence is in tatters after Jeremy Corbyn ruled out ever using Britain’s nuclear deterrent, refused to back a drone strike to kill Isil’s leader and said he would suspend air strikes on Syria.

Within hours of his interview, the Labour Party was forced to issue an embarrassing statement clarifying that it still supports the Trident nuclear deterrent.

Jeremy Corbyn, the Labour leaderCredit:
Danny Lawson/PA

Sources close to Mr Corbyn said his own advisers were left “pulling their hair out” over his appearance, during which Mr Corbyn said he was a not “supporter or defender” of Islamic State of Iraq and the Levant (Isil).

Lord Richards of Herstmonceux, a former chief of defence staff, told The Daily Telegraph: “Jeremy Corbyn, unlike many of his distinguished predecessors in the Labour Party from Clement Attlee through Dennis Healey and beyond, has demonstrated why he should not be trusted with the ultimate responsibility of government – that of the nation’s defence and security.”

Lord West of Spithead, a former First Sea Lord and Labour security minister, said his comments risked alienating the Armed Forces. He said: “By speaking in that convoluted way, he makes the average member of the Armed Forces think ‘Is this guy supporting us or not?’”

Mr Corbyn, a lifelong opponent of nuclear weapons, suggested in his first major broadcast interview since Theresa May called a snap election that he would not authorise nuclear strikes under “any circumstances”.

In comments to BBC One’s The Andrew Marr Show which directly contradicted Labour’s official policy, Mr Corbyn said: “I have made clear my views on nuclear weapons. I have made clear that there would be no first use of it. I have made clear that any use of nuclear weapons is a disaster for the whole world.

“I think we should look at the process by which we achieve peace and security because actually nuclear weapons are not the solution to the world’s security issues, they are the disaster of the world’s security issues if ever used.”

Jeremy Corbyn on The Andrew Marr ShowCredit:
Jeff Overs/BBC/PA

The Labour leader was asked what he would write in his “letters of last resort” to British nuclear submarine commanders. The letters dictate what they should do in the event Britain is subject to an attack.

He said his letter would instruct the four commanders only to “follow orders when given”.

Mr Marr replied: “So you don’t tell them to fire or not to fire? They don’t know what to do?”

Mr Corbyn then went further and suggested that he was prepared to scrap Britain’s Trident nuclear deterrent entirely, revealing that a Labour Government will launch an immediate defence review.

Amber Rudd, the Home SecretaryCredit:
Daniel Leal-Olivas/AFP

A Labour spokesman later said: “The decision to renew Trident has been taken and Labour supports that.”

Mr Corbyn also suggested that he would be reluctant to authorise a drone strike against Abu Bakr al-Baghdadi, the leader of Isil.

He added: “What I would tell them is give me the information you have got, tell me how accurate that is and tell me what you think can be achieved.

“What is the objective here? Is the objective to start more strikes that may kill many innocent people as has happened or is the objective to get a political solution in Syria? My whole point would be does this help to get a political solution in Syria?”

Jeremy Corbyn outside his home on Sunday morningCredit:
Fiona Hanson

He subsequently added: “I think the leader of Isil not being around would be helpful and I’m no supporter or defender in any way whatsoever of Isil, but I would also argue that the bombing campaign has killed a large number of civilians, many of whom were virtually prisoners of Isil, you have got to think about these things.”

The Labour leader also called for an end to RAF air strikes in Syria. He said: “At the end of the day the only solution in Syria is going to be a political one. There is no other way of getting it. There has to be a reconvening quickly of the Geneva process.

“I would say to President Trump, listen, it’s in nobody’s interest for this war to continue, let’s get the Geneva process going quickly and in the meantime no more strikes, have the UN investigation into the war crime of the use of chemical weapons in Syria and take it on from there.”

The Labour leader said that he wants to pursue a “sensible relationship” with Russia and suggested he would bring home 800 British troops currently stationed in Estonia as part of a Nato operation.

A succession of Labour MPs distanced themselves from their leader, warning that he would not make a good Prime Minister and urging voters to back the party rather than Mr Corbyn.

One Labour MP told The Daily Telegraph: “If that’s the start of week one, God knows what we will be like in week seven. It was as though he is continuing his 30-year career as a back-bench MP. It’s going to be a disaster.”

Amber Rudd, the Home Secretary, criticised Mr Corbyn's comments.

She said: “This morning we learnt that Jeremy Corbyn would refuse to strike against terrorists, dismantle our nuclear defences and fail to control our borders.

“Unless people turn out and vote Conservative, this man could be our Prime Minister in less than 7 weeks’ time - propped up by the SNP and Lib Dems in a coalition of chaos.

“For strong and stable leadership as we approach Brexit and beyond it is critical to vote for Theresa May and her Conservative team on 8 June. Every vote in this election counts.”